JPH05315841A - Double voltage detection circuit with temperature compensation - Google Patents

Abstract

PURPOSE:To supply a detection circuit to a high frequency detection circuit by deciding a responsiveness of the high frequency detection circuit with only a smoothing circuit constant at the output of the detection circuit so as to have only to slightly adjust a temperature compensation voltage. CONSTITUTION:A high input impedance type adder 2 consists of noninverting operational amplifiers 21, 22 and an inverting operational amplifier 23. An output D[(RV/R)+1] properly set is obtained at the output of the operational amplifier 21 based on an output voltage D generated from the operational amplifier 21 receiving a voltage drop by a forward current flowing to a 3rd diode D3 with a high input impedance via the diode whose other terminal is connected to ground (OV) through the use of a fixed resistor R and a variable resistor RV at the output side. The output D[(RV/R)+1] and an output C resulting from the operational amplifier 22 receiving an output C of the double voltage detection circuit with a high input impedance and outputting it as it is are summed. Then the operational amplifier 23 inverts the polarity and outputs an output E=-D[(RV/R)+1]-C as a detection output voltage. Thus, even when the characteristic specification of the diodes D1, D2 and the frequency of a detected output signal are subjected to change, it is coped by slightly changing the resistor RV.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention adds a temperature compensating diode to a diode circuit for detecting a high frequency signal used in a device such as an AGC circuit of a high frequency amplifier of a communication device in which a change in output level is a problem due to temperature. The present invention relates to a high-frequency detection circuit with temperature compensation.

[0002]

2. Description of the Related Art A conventional high frequency detection circuit with temperature compensation is
As shown in the circuit diagram of Fig. 5, input terminal t3 for high frequency signal Vin
A second diode D2 is connected between the output side of the detection diode D1 connected to and the ground and the detection diode D1 so that the same current with the same polarity as the direct current flows with the resistor R5. Further, a voltage V _B ′ obtained by adding the DC voltage at the connection point of the resistor R5 and the second diode D2 and the DC voltage V _B for external bias by the operational amplifiers 24 and 25.
, A high-frequency blocking circuit L that allows direct current to pass but blocks high frequencies
It was configured to supply to the detection diode D1 through 7, C8.

[0003]

The conventional high-frequency detection circuit with temperature compensation requires the high-frequency blocking circuits L7 and C8 as described above, and it is necessary to consider the selection of the constants. Therefore, this detection circuit with temperature compensation is
When used in a GC circuit, etc., the frequency characteristics of the smoothing circuit L11, C9, C10 of the detection circuit and the high frequency blocking circuit L7, C when designing
There is a problem that it is complicated because it is necessary to consider it together with the frequency characteristics of 8. An object of the present invention is to use two detection diodes in order to increase the detection efficiency, and in a high-frequency voltage doubler type detection circuit that can obtain a detection voltage twice as high as that of one detection diode, the characteristics of the detection diode are used. Even if there is a change in the specifications or the frequency of the output signal to be detected, it is to realize a high-frequency detection circuit with temperature compensation that can immediately respond to the change.

[0004]

The basic configuration of the present invention for achieving this object is shown in the principle diagram of FIG. In the figure, 1 is the same characteristic as the detection diodes D1 and D2 in the voltage doubler type detection circuit using the first and second detection diodes D1 and D2, one each on the input side and the output side of the high frequency signal. a third diode D3 which generates a compensation voltage, to between the resistors R ₁ voltage doubler detection and smoothing circuit C ₂ of the output of the _unit, R ₁ and the ground, with respect to the second diode D2 DC current Are provided so that the same current flows with the same polarity. Reference numeral 2 is a high input impedance type adder for adding the output obtained by adjusting the output voltage of the one-side ground of the third diode D3 to an appropriate value and the output of the voltage doubler type detection circuit with high input impedance.

[0005]

In the present invention, the third diode D3 for temperature compensation is used.
Has the same characteristics as the first diode D ₁ and the second diode D ₂ for detection, and is provided between the resistor R ₁ of the smoothing circuit C _2, R ₁ of the output of the high frequency voltage doubler type detection circuit and the ground. It is in, and the second diode D2 the same current flows in the same polarity with respect to direct current, a first diode D _1, with a value equal to the temperature variation in the voltage drop due to second diode D ₂ in the forward current It causes a voltage drop. Then, a high input impedance type adder (2) such as an operational amplifier adds the output obtained by adjusting the output voltage of the third diode D3 to an appropriate value and the output of the voltage doubler type detection circuit and outputs the result. Then, the temperature change in the voltage drop due to the forward currents of the first diode D ₁ and the second diode D ₂ is corrected by the output voltage of the third diode D ₃ having an appropriately adjusted polarity, A temperature-compensated detection output voltage is obtained. Therefore, even if such a change frequency of the voltage doubler type detection circuit detection diode D _1, D ₂ properties specifications and the output signal of the detection of occurring, only a slight adjustment of its left or variable resistor Rv, its Can respond to changes immediately.

[0006]

FIG. 2 is a circuit diagram of a voltage doubler detection circuit with temperature compensation according to an embodiment of the present invention, and FIG. 3 shows waveforms of respective parts for explaining the operation of only the voltage doubler detection circuit. FIG. 4 shows the waveform of each part for explaining the operation of the voltage doubler type detection circuit with temperature compensation according to the embodiment of the present invention. The circuit (1) in Figure 3 is
The configuration of the voltage doubler type detection circuit is shown below. (2) IN voltage in the figure is
Indicates the high frequency input voltage at the input terminal IN. And (3) a in the figure
Point voltage indicates the voltage of the anode a point of the first diode D1 in the same circuit, a voltage caused by the forward current of the diode D ₁
The upper part is reduced by v and the lower part is cut. (4) Point b voltage in the figure indicates the voltage at the point b of the anode of the second diode D2 cascaded to the first diode D1 (provided that the smoothing circuits C2 and R1 for the detection output are not provided). The dotted line shows the case where no forward current flows through the second diode D2, and the solid line shows the case where the forward current flows through the second diode D2 and is reduced by the voltage v and cut. The (5) OUT voltage in the figure shows the detection voltage at the output terminal OUT when the detection output smoothing circuits C2 and R1 are present. The voltage drop due to D _{1 and} D ₂ from the maximum value of the detected voltage includes the change due to the temperature of the forward current of D _{1 and} D ₂ . In the embodiment of FIG. 2, the third diode is provided between the resistor R1 of the smoothing circuit C2, R1 of the output C of the voltage doubler type detection circuit composed of the first diode D1 and the second diode D2 and the ground (0v). provided D3, generates a voltage D to compensate for changes caused by temperature in the voltage drop of the D _1, D ₂ of the forward current.
That is, the third diode has the same characteristics as the first and second diodes D1 and D2 and the second diode D2 has the same polarity and the same current with respect to the DC current to generate the DC voltage D.
Provide D3. The high input impedance type adder 2 is composed of non-inverting operational amplifiers 21 and 22 and an inverting operational amplifier 23, and the non-inverting operational amplifier 21 operates as a third diode D3.
The other end of the output is grounded (0v) and the output voltage D generated by the forward current is input with a high input impedance, and the output side fixed resistor
Output D [(Rv / R) +1] with an appropriate value by R and variable resistor Rv
And the non-inverting operational amplifier 22 outputs the output C of the voltage doubler type detection circuit.
Is combined with high-impedance input C and output as it is, the sign is inverted by the inverting operational amplifier 23, and the output E = -D [(Rv / R) +1] -C is output as the detection output voltage. Therefore, even if the characteristic specifications of the _two detection diodes D _{1 and} D ₂ of the voltage doubler type detection circuit or the frequency of the detection output signal changes, it is possible to change the variable resistance Rv as it is. , You can immediately respond to the change.

[0007]

As described above, in the conventional method, the frequency characteristic of the high frequency blocking circuit in the direct current path of the bias supply to the temperature compensating diode was also involved in the response characteristic of the high frequency detecting circuit. In the high-frequency detection circuit, its response characteristics are determined only by the constant of the smoothing circuit of the output of the detection circuit, so without changing the characteristics of the temperature-compensated circuit, or just by slightly adjusting the temperature compensation voltage, The effect that can be immediately applied to the high frequency detection circuit is obtained.

[Brief description of drawings]

FIG. 1 is a principle diagram showing a basic configuration of a voltage doubler detection circuit with temperature compensation according to the present invention.

FIG. 2 is a circuit diagram of a voltage doubler detection circuit with temperature compensation according to an embodiment of the present invention.

FIG. 3 is a waveform diagram for explaining the operation of only the voltage doubler detection circuit according to the embodiment of the present invention.

FIG. 4 is a waveform chart of each part for explaining the operation of the voltage doubler detection circuit with temperature compensation according to the embodiment of the present invention.

FIG. 5 is a circuit diagram of a conventional high-frequency detection circuit with temperature compensation.

[Explanation of symbols]

1 is a third diode D ₃ for temperature compensation, 2 is a high input impedance adding circuit, 21 and 22 are non-inverting operational amplifiers, 23
Is an inverting type operational amplifier.

Claims (1)

[Claims] 1. A first and second detection diode (D1, D2) is used for each of an input side of a high frequency signal and an output side for detecting and outputting the high frequency signal. The second diode of the double voltage type detection circuit that outputs the double detection voltage.
The second diode is connected between the output resistor (R ₁ ) of (D2) and the ground so that the same current flows with the same polarity with respect to the DC current. The diode (1) is connected, and the output of the _third diode (D ₃ ) with the voltage between both ends adjusted appropriately and the output of the voltage doubler type detection circuit are added by the high input impedance type adder (2). A voltage doubler detection circuit with temperature compensation, which outputs.